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Comment by dinkblam | Hacker News Reader

saving 30 kg of weight on a 2000 - 2500 kg car won't lead to "significant efficiency gains"

The Ferrari 296 GTB weighs about 1500kg and the sports version 1300kg. For the cars YASA produces motors for it's much easier to increase the power to weight ratio by reducing weight than increasing power. I imagine an important design point for all of its components is to reduce weight.

Also as mentioned by another comment, Mercedes produces Formula 1 power units, and engineers would kill for a savings of a few kilograms in Formula 1. Those savings are not easy to come by.

Weight reductions on an electric car are self-reinforcing. If you reduce the weight of a component, the battery can become (slightly) smaller, which again reduces weight. At a certain amount of reduction this will allow you to make the whole structure lighter, which will again allow for a smaller battery.

So yeah, weight reduction on EVs is great.

Also not considered is that the announcement is for 740bhp motor. The Tesla model 3 has a vehicle output of about 400 hp. I’m not sure of all the design specs, but it seems clear to me that a smaller version of these motors could suffice to drive a 3 equivalent vehicle at 1/2 the output and still be more than sufficient. So let’s say maybe 15lbs each, vs current equivalent 70lbs each. It’s not major total weight impact, but with battery advancements it will compound.

I think people are overlooking that the announcement is for a performance motor meant for the performance market at the moment because that is what the backers of YASA are most interested in because it has the highest margins and prestige. Also not mentioned is the efficiency from the simpler production line.

My impression from what I know is we are looking at an impact equivalent to direct injection engines; not revolutionary, but a major advancement of one component that has significant and consequential effects.

The e-motor is often “overpowered” in EVs (compared to ICEs) to make regenerative braking efficient, i.e. capture meaningful energy from braking.

And because almost everyone is a sucker for the "Stomp on the pedal and it goes fast" marketing strategy and demonstration.

That's why a modern Camry makes almost 200 HP

It's also just a lot easier and cheaper to make an electric motor "overpowered" by 25% or even 50+% than an internal combustion engine.

> If you reduce the weight of a component, the battery can become (slightly) smaller

Suppose we have a motor that weighs half as much, but produces double the output power, but consumes 4x the input power (so, it is half as efficient).

How would that lead to a smaller battery?

Wouldn't we need the component to use less power if we wanted to shrink the battery, rather than just weigh less?

I agree insofar as the motor is not a Big Ticket Item, opposed to ICE cars where the engine block is going to be 10% or more.

Tesla (I know) claimed a 30kg (?) weight loss on their Cybertruck (I know) just from moving their 12V systems to 48V, allowing for lighter cables at lower currents. Not all such potential is untapped, and my hunch is that there is more to be had with structural battery integration, battery cooling, and high voltage wiring.

Depends on your definition if significance, but I think they do. Every kg of useless weight you do carry, lowers your range. But sure, on its own it is not a magic game changer for heavy electric cars.

For light weight vehicles on the other hand, it might be.

If you put several small motors on each wheel you might get some extra weight gains in the form of less transmission needed. Cables weight less than metal structural bars. But yes you are not going to be 500kg lighter.

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